I think this topic has been discussed before, so I don't know how much of my response will simply be a repeat of previous posts.

Dojo are places of training and sensei is responsible for maintaining the safety and sanctity of the environment so students feel comfortable training. One of those decisions may involve the alignment of goals, values, and expectations of the students within the dojo. I would not argue this alignment is discrimination but it creates an inclusive demographic of the dojo members. I think this type of alignment should be done openly and with consistency. The student is then empowered to make a decision to train in the dojo within a set of "rules" that are public and enforceable. I think each dojo faces smaller decisions which establish the line in the sand for larger issues, and those decisions should remain variable to fit the conditions, location, and culture in which the dojo is situated.

1. For those sensei who make poor decisions about what their dojo should represent, their dojo will fail. Discerning students who do not align with that instructor's goals and expectations will choose not to attend class.
2. Training is conditional gift. If a student is unwilling to accept the conditions of the gift they should not expect to receive the gift.

Taken to another level, why would New York Mets fans attend a Yankees game? Why would a republican attend the Democratic National Convention? Why would a math major spend her time studying English? We spend our time aligning ourselves with activities, friends, and lifestyle to match our beliefs. Why would I walk into a dojo that does not share those beliefs, then demand that they change to accommodate me? The friction will be larger than just what you see on the mat...